Method of connecting carrier frequency to a double circuit



Aug. 19, 1941. w. E. PAKALA 2,253,393

` N'I'L'I'IOD` OF CONNECTING CARRIER FREQUENCY TO A DOUBLE CIRCUIT Filed Feb. 4, 1939 wlTNr-:ssEs: i INVENToR IA///a/nf. Palm/a.

ATTORNEY Patented Aug. 19, 1,941

METHOD F CONNECTING CARRIER FREQUENCY T0 A DOUBLE CIRCUIT William E. Pakala, Forest Hills, Pa., assigner to Westinghouse Electric 'sa Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 4, 1939, Serial No. 254,619

6 Claims.

. branch feeder lines to a pair of high frequency s conducting vcoaxial cables so that two separate carrier wave circuits are provided which allows the use of at least one of the carrier circuits in the event that one of thebranch lines should break or otherwise Abecome inoperative.

Another object of my invention is to provide a carrier Wave transmission system including a pair of circuits, at least one of which is operative in the event that one of the feeder wires becomes inoperative and in which a minimum amount ci energy loss is present under such conditions.

lOther objects and advantages will become more apparent from -a study of the following specification when considered in conjunction with the accompanying drawing which schematically shows a circuit embodying my invention.

y Numeral I denotes a three-phase power line which feeds a pair of parallel branch lines 2 and 3, one of which acts as an emergency line in the event that the other line becomes inoperative. Across terminals 4 and 5, which are on ,lines of different phase relationship, are connected, in seriescondensers 8 and 1, choke coils 8 and 9, primaries I8 and II of two separate and independent transformers A and B and a pair of ground connections I2 and I3 which are metallically connected to a station ground system. A pair of coaxial type cables I4 of substantial length form a carrier for high frequency current which is fed across terminals 4 and 5. Each of the cables comprises a center wire I5 and a substantially cylindrical coaxial sheath I8 separated by insulating 'materials I1. The cable is shown partly dotted to indicate its substantial length. The secondaries I8 and I9 of the above-menti'oned transformers are connected in series across the centerwires of the cables at one end of the cables. tween the sheaths of both ofthe cables at the same enel thereof to an intermediate point between the secondaries I8 and` I9. At the other end of the cables I4, there are provided an electrical transmitter 2| and an electrical receiver 22. The transmitter includes four grid controlled .A thermionictubes 23, 24, 25 and 26 and a pair of separate output transformers 21 and 28, the primary terminals of which are connected to -lthe A connection is provided be,

plates 29 to 32, inclusive, of tubes 28. to 26, in-

clusive, respectively. Grids 33 and 3'4 of tubes 23 and 25 are interconnected and likewise grids 35 and 36 of tubes 24 and 28, thus forming a push-pull arrangement. A positive source of plate potential denoted as B+ is applied to central points on the primary windings of the output transformers 21 and 28. The receiver 22 cornprises a plurality of-transformers 31 and 38; a plurality of variable condensers 39, 48, 4I and 42, a grid leak` 48 and a pair of thermionic tubes 44 and 45 in circuit relation, as shown in the drawing.

The` receiver is fed by two separate input transformers 46 and 41, the primaries and secondaries of which are each connected in series relation, as shown.` Theprimary coils 48 and 49 of the receiver are connected in series relation with respect to the secondaries 58 and 5I of the'trans- The terminals of the series connectedmitter. transmitter secondaries 58 and 5I and of the series connected receiver primaries 48 and 49 are connected by means of conductors 52 and 53 to the central wires at the lower end of cables I4. A conductor 54 connectsthe intermediate points between windings 58 and 5I and between windings 48 and 49, thus forming a third Wire which, in turn, is connected byV means of,V conductor 55 to the sheaths of the lower end of cables I4.

The operation of the device is as follows: A v

` carrier circuit between terminals 4 and 5 and is induced in the secondary windings I8 and I9, andy is conducted by means of the center wires I5 to the other end of the cable to conductors 52 and 53, thus introducing the carrier wave in thev circuit including the series connected windings 50 and 5I and the series connected windings 48 and 49. The above description is for reception of signals. In the case of transmission of signals, the flow of power is from conductors 52 and 53 toward terminals 4 and 5. No current will be conducted through the conductors 54,l 55, the

v sheaths I6 and conductor 28 if the system is balanced. In the event, however, that a break in the line should` occur, for example, at point 58, or that the line 3 should otherwise become inoperative, a separate input circuit is established across primary I8 and secondary I8. Conductor 28 and the sheath I8 of the left cable and conductors 5,4 and 5,5 now carry the same current at half the total original voltage (one-half total power output) now being introduced solely through the medium of conductors 52 and 54 across windigs 48 and` 58 only. The circuit inand ineffective to carry power. It will thus be seen that the power transmission is half of its initial value. Furthermore, the conductor 54 linstead of carrying no current carries thev `same current as windings 50 and 48. This comprises a highly efficient system as compared with previously used coupling connections in which a break of one line would cause losses up to the neighborhood of 90% and would make the remaining circuit inoperative due to its inability to carry sufficient power.v

In previous coupling connections well known in the art, the third wire (i. e., conductor 54) was not used, nor was the connecting sheath used. Instead, the secondary windings I8 and I9 were connected through cables I4 to conductors 52 and 53 only, without the neutral or third wire. Hence, when a break would develop, such as at point 56, this would be equivalent to an open circuit in winding II the effect of which is to increase the impedance of winding I9 due to the opening in its magnetically coupled winding I I to about ten times its normal value; hence greatly reducing the current in the circuit through windings I8 and I9 and in the receiver transformer windings--in fact, so greatly reducing the current that the remaining power would be rendered ineffective to produce signals in the receiver circuit. Likewise, the high impedance of coil I9 made' it substantially impossible to transmit sufciently strong signals in transmitter 2| across the terminals l and 5.

It should be noted that the drawing shows a single transmitter and receiver station, it being understood that a similar transmitter and receiver station, or similar transmitter and receiver stations, are'connected across other points than terminals Il and in the same lines throughout the length of lines 2y and 3. It is understood further that any wire of line 2 can be interconnected with any wire of line 3 to form the carrier circuit for the high frequency carrier wave and instead of using two branch lines 2 and 3,

, there may be any number of similar branch lines.

It lis understood also that, although coaxial cables I4 are shown, any other equivalent cable may be used for carrying the high frequency carrier wave to and from terminals and 5.

I am, of course, aware that others, particularly after having had the benefit of the teachings of my invention, may devise other devices embodying my invention, and I, therefore, do

`not wish to be limited to the specific showings pair of separate transformers, the primaries of which are connected in series across a pair of wires, one from each of said pair of branch lines, a gnound connection between the primaries, and the secondaries of which are connected in series across the rst corresponding ends of the said second conductors, Van electrical device, a second pair of transformers having primaries which volving ywinding I9, the right-hand cable and the windings 49 and 5I, of course, is inoperative are connected in series across the other corresponding ends of the said second conductors and having secondaries which are connected to said electrical device, a connection which interconnects the intermediate points'between the secondaries of said first pair of transformers and the first corresponding ends of the said ilrst condu-ctors, and a connection connecting the intermediate points of the primaries of said second pair of transformers to the other correspending ends of the said first conductors.

2. An electrical transmission system comprising-a three-phase power line, a pair of threephase branch lines each comprising three wires and which lines are connected in parallel and are fed from said power line, a high frequency carrier line comprising a pair of parallelly disposed coaxial type cables each of which includes a central wire and a substantially cylindrical and coaxial sheath, a pair of separate transformers the primaries of which are connected in series across a Ipair of wires, one from each of said branch lines, a ground connection between the primaries, and the secondaries ol.' which are connected in series across the ends of the central wires at one' end of said pair of cables, a connection from an intermediate point between said secondaries to both ends of said sheaths at said one end of the cables, an electrical device, a second pair of separate transformers the secondaries of said second pair of transformers being connected to said electrical device and the primaries thereof being connected in series across the ends of central wires at the other end of said cables, and a connection between an intermediate point between said last mentioned primaries and both ends of said sheaths at said other end of said cables. l

3. An electrical transmission system comprising a three-phase power line, a pair of threephase branch lines each comprising three Wires and whichv lines are connected in parallel and are fed from said power line, a high frequency carrier line comprising a pair of parallelly disposed coaxial type cables each of which includes a central wire and a substantially cylindrical and coaxial sheath, a pair of separate transformers the primaries of which are connected in series across a pair of wires, one from each of said branch lines of different phase relationship, a

,ground connection between said primaries, and

the secondaries of which are connected in series across the ends of the central wires at one end of said pair of cables, a connection from an intermediate point between said secondaries to both ends of said sheaths at said one end of the cables, an electrical receiving device, a second pair of separate transformers the secondaries of said second pair of transformers being connected to said electrical receiving device and the primaries thereof being connected in series 'across the ends of the central wires at the other end of said cables, and a connection between an intermediate point between said last mentioned primaries and both ends of said sheaths at said lother end of said cables.

4. An electrical transmission system comprising a three-wire three-phase power line, a pair of three-phase branch lines each comprising three wires and which lines are connected in parallel and are fed from said power line, a high frequency carrier line comprising a pair of parallelly disposed coaxial type cables each of which includes a central wire and a substantially cylindrical and coaxial sheath, a pair of` sepanate transformers the primaries of which are connected in series across a pair of wires, one from each of said branch lines, a ground connection between said primaries, and the secondaries of which are connected in series across the ends ofthe central wires at one end of said pair` of cables, a vconnection from an intermediate point between said secondaries to both ends of said sheaths at said one end of the cables, an electrical receiving device, a second pair of separate transformers the lsecondaries of said second pair of transformers being connected to said electrical receiving device and the primaries thereof being connected in series across the ends of the central wires at the'other end of said cables, an electrical transmitter device having separate output transformers, the primaries of which are connected to said transmitter and the secondaries of which are connected in series and across the ends of the central wires at said other end of said cables, a connection be. tween the intermediate points of the secondaries of said transmitter device, the primaries of said receiver device and both ends of the sheaths of said other end of said cables.

5. An electrical transmission system comprising a three-wirethree-phase power line, a pair of three-phase branch lines each comprising three wires and which lines are connected in parallel and are fed from said powerline, a high frequency carrier line comprising a pair of panallelly disposed coaxial type cables each of which includes a central `wire and a substantially cylindrical and coaxial sheath, a pair of separate transformers the primaries of which are connected between them in series with a ground connection and with a pair of condensers across a pair of wires, one. from each of said branch lines, and the secondaries of which are connected in series across the ends of the central formers, the primaries of which are connected to said transmitter and the secondaries of which are connected in series and across the ends of the central wires at said other end of said cables, a connection between the intermediate points oi the secondaries of said transmitter device, the primaries of said receiver device and both ends of the sheaths of said other end of said cables.

6. `An electrical transmission system comprising a three-wire` three-phase power line, a pair of three-phase branch lines each comprising three wires and which lines are connected in parallel and are fed from said power line, a high frequency carrier line comprising a pair of parallelly disposed coaxial type cables each of` which includes a central wire and a substantially cylindrical and coaxial sheath, a pair of separate transformers the primaries of which are connected in series across a pair of Wires, one from each of said branch lines, a ground connection between `the primary windings, and

the secondaries of which are connected in series across the-ends of the central wires at one end of said pair of cables, a connection from an intermediate point between said secondaries to` both ends of said sheaths at said one end of the cables, an electrical receiving device, a. second pair of separate transformers the secondaries of wires at one end 'of said pair of cables, a conl nection from an intermediate point between said secondaries to both of said sheaths at said one end pf the cables, an electrical receiving device, a second pair of separate transformers the secondaries of said second pair of transformers being connected to said electrical receiving device and the primaries thereof being connected in series across the ends of the central wires oi' the other end of said cables, an electrical transmitter device having separate output transsaid second pair of transformers being connected to said electrical receiving device and the primaries thereof being connected in series across the ends of the central wires of the other end of said cables, an electrical transmitter device having separate output transformers, the primaries of `which Vare connected tosaid transmitter and the. secondaries of which are connected in series and across the ends of the central wires of said other end of said cables, a connection between the intermediate points of the secondaries of said transmitter device, the primaries of said `receiver device and both ends ofthe sheaths of said other end of said cables. said transmitter kdevice including four gridcontrolled thermionic tubesyeach of which in-` cludes a cathode, grid and plate, and the plate of which tubes are connected to the four primary,

terminals of said output transformers,` the grids of each pair of thermionic tubes whose plates are connected to different primaries of said transmitterA being interconnec WILHAM E. PAKALA. 

